This invention relates to a system for applying the effects of high-energy ion radiation upon materials, semiconductors, insulators and the resultant function or malfunction of electronic or optical circuits and discrete devices and, more particularly, to a system for correlating the impact point of an ion measured by projection imaging of ion-induced photons with the effect of that ion upon the sample itself.
The signal produced by the emission of photons from a sample bombarded by high energy (MeV) ions has been used for many years on conventional nuclear microprobes, and on almost all accelerators, for viewing the beam during focussing and other beam adjustments such as steering and scanning. For these purposes the photons are not imaged. They are merely observed visually through high power microscopes or with charge-coupled device (CCD) cameras.
A physics application has emerged from this science, which is called lonolumenescence which has been extensively applied in the field of Geology. In lonolumenescence, a beam of ions is focused and then scanned across a sample specimen while measuring the intensity or in some cases the actual energy spectrum of emitted photons. Other applications have arisen in fields such as biology, where luminescent microscopes have been developed for studying biological objects (U.S. Pat. No. 6,088,097, issued on Jul. 11, 2000).
Nuclear microprobe analysis is currently performed by focusing MeV ions onto a sample and then scanning the ion beam in a flying spot analysis. The nuclear, atomic, or charge collection signals that are created by the interaction of the ions with the sample constitute the detected signal. The location from which the signal originates on the sample is known by the position of the scanning ion beam at the time the signal is created and detected. The position of the xe2x80x9cflying spotxe2x80x9d is derived from the scanning apparatus that moves the focussed ion beam spot back and forth across the sample. This standard nuclear microscopy is not always applicable in certain accelerator laboratories due to the difficulty in focussing ions with high magnetic rigidity and/or poor beam chromaticity for cyclotrons, linacs and older Van de Graaff style electrostatic ion accelerators. There can also be problems in clearly forming the object image for standard microbeam systems when the depth of penetration in slit materials (for very high ion energies) becomes comparable to the object slit diameter. High-energy accelerator labs can also have higher levels of radiation in the target areas, making hands-on real-time adjustments of the microbeam system and direct viewing of the beam spot on fluorescing materials impossible. This seriously complicates the procedures used in most microbeam applications to obtain an optimal beam focus.
Alternatives to traditional nuclear microprobe analysis emerged with the invention of Ion-Electron Emission Microscopy (IEEM) (Doyle, B. L., Walsh, D. S., Vizkelethy, G., Senftinger, B, Mellon, M., 1999, Nucl. Insts. and Meth. in Phys. Res, B, 158, 6). With Nuclear Emission Microscopy, the ion beam is only partially focused so as to fill the field of view of a special emission particle microscope system fitted with a single particle Position Sensitive Detector (PSD). When a single ion strikes the sample, the emitted secondaries (e.g. electrons, photons, ions) are projected at great magnification onto this PSD where position signals are generated. These X and Y signals are then put into coincidence with other signal made by this same ion in a fashion completely analogous to traditional nuclear microprobe analysis. These Nuclear Emission Microscopes techniques currently includes IEEM and Highly Charged Ion-Secondary Ion Mass Spectroscopy (HCI-SIMS) (Doyle, B. L., Walsh, D. S., Renfrow, S. N., Vizkelethy, G., Schenkel, T., and Hamza, A. V., 7th Intl. Conf. on Nuclear Microprobe Tech. and Appl., 2000; incorporated herein by reference). These techniques utilize accelerators to provide the ion beam.
A microbeam apparatus would be useful that does not require an accelerator and that can obtain simultaneous information on the characteristic of a sample when impinged by an ion as well as the position of the ion strike.